I did some speed runs today to test out a couple of different batteries that I have. I hit a new best of 62 mph on 2S! I made no other changes to the truck and I made several passes to ensure consistency. I'm using the Garmin Forerunner 101 for my GPS.
Motor - Castle 1406 5700kv (540 can)
ESC - Mamba Max Pro
Tires - Jaco Foams
Gearing - 43/50
57.3 mph with Boost 2S 2450mah 50/90c (in parallel)
61.9 mph with Thunder Power 2S 2250mah 65c (in parallel)
So I picked up almost 5 mph just by changing batteries. So for everyone getting a big block, you can see how important it is to choose a quality and high c rating battery. If you had a 30c battery, it would be even worse.
I tried running my Boost 3S 1800mah 45/55c (in parallel), and they're really struggling to feed this motor. Plus I think one of the cells may be starting to go bad. I would love to have some of the new Thunder Power G8 Pro Force 3S 70/140c batteries, but man they're expensive.
I also tried lowering the truck as low as it could go and it didn't go any faster, so aerodynamics are not an issue at 60 mph.